Little useful information was found on the effects of logging on Bornean reptiles (but see Meijaard et al., in press). Hunting and collecting, however, has significantly reduced (locally to extinction) populations of terrestrial and fresh water turtles and crocodiles.
Rachmatika et al. (unpublished) conducted extensive surveys of the fish faunas of the upper and lower Seturan River in the Malinau area. Among others they investigated how fish species are affected by logging. The results showed that hillstream loaches and other site-specific demersal species (Gastromyzon spp., Garra borneensis, etc.) seem the most affected but some benthopelagic herbivorous or frugivorous species (Lobocheilos bo and Tor spp.) also appear absent in logged areas. Rachmatika et al. reported that these results are coherent with the life-history of the species present and with the few available published references (Martin-Smith 1998a,b). Given their low mobility, their sensitivity to siltation and their general abundance in undisturbed sites, the suckerbelly loaches (Gastromyzon, Neogastromyzon, Protomyzon) and the stone-lapping minnow (Garra borneensis) could be used as early warning bioindicators for monitoring logging impact.
A very depauperate fauna characterized ponds and their outlets, and a total of only 16 species was recorded from this type of environment. All the vulnerable demersal species were absent except for one specimen of Anguilla malgumora at the outlet of one of the ponds. Some species appeared, however, to be over-represented in ponds: Cyclocheilichthys armatus, C. repasson, Nemacheilus saravacensis (36%), Puntius sealei (29%). Betta unimaculata seemed to prefer outlets and was absent or rare in the ponds proper.
Several of the surveyed species present specific auto-ecological or biological features that might be of importance in the context of existing logging or coal-mining operations in the region. Since demersal species live on or near the river bottom and feed on benthic organisms, they could be affected by excessive siltation created by logging infrastructure (culverts, crossing of river by heavy equipment, etc.). Eels (Anguilla), spiny eels (Mastacembelus, Macrognathus), bagrid (Leiocassis sp., Hemibagrus spp.) or sisorid catfishes (Glyptothorax platypogonoides), hillstream loaches (Gastromyzon, Neogastromyzon, etc.) are all demersal fishes.
Other potentially vulnerable species are the benthopelagic fishes that feed on micro-algae (Lobocheilos bo, some Osteochilus sp., Tor spp.) or forest fruits and plants (Leptobarbus melanotaenia, Tor spp.). These fishes can be affected by a reduction in food availability following logging.
In this paper we have documented the responses of a wide range of vertebrates to the effects of logging. Although vertebrate species vary widely in their ecological requirements there appear to be common determinants of the effects of logging on their survival. Maintaining a dense and moist understorey seems to be particularly important for many species. Also maintaining connectivity between forest patches appears important, as is the protection of fruit trees such as figs and retaining dead wood. Meijaard et al. (in press) also discussed the effects of hunting, which often affect species much more than logging itself (Bennett et al. 2002). Although this is a generalization — e.g., in some areas of Java and Sumatra little hunting takes place, but species are seriously threatened by forest loss (e.g., Robertson & van Schaik 2001; Kinnaird et al. 2003; Hedges et al. in review) — it is probably true for most parts of Borneo. Despite the successful establishment of many protected areas where the forest remains largely untouched by logging, many of these areas are increasingly becoming ‘empty forests’ (Redford 1992). The threat posed by hunting is especially great in tropical forests, because of the extremely low productivity of edible wildlife (Bennett et al. 2002). Hunting is likely to lead to changes in wildlife population densities, distributions, and demographies which can then lead to shifts in seed dispersal, browsing, competition, predation, and other community level dynamics. How all these factors relate to each other remains unclear, but the overall result is that most larger vertebrates in Borneo and some specifically targeted species such as turtles, crocodiles, ungulates, and certain birds have in many areas been hunted to virtual extinction (Bennett et al. 1997; Bennett et al. 1999; Robinson et al. 1999; Bennett & Robinson 2000).
The three factors of logging, fragmentation and hunting often occur simultaneously, and it is not always possible to determine the individual contribution of each factor to a perceived population decrease or increase of certain species—indeed they will almost certainly act together. Lambert and Collar (2002), who analyzed existing datasets on birds, stated that there appear to be fundamental differences between the effects of logging and fragmentation on Sundaic lowland forest species. Selective logging usually results in the loss or extreme rarefaction of certain insectivorous species, particularly those of the dark understorey and in terrestrial foraging guilds, but there is little evidence of intolerance to logging in the majority of frugivorous and nectarivorous species. Also, arboreal and canopy species that primarily feed on fruit were much less affected, or even benefited from some logging. This mirrors findings by Crome et al. (1996) who similarly found that few, if any, bird and small mammal species, were negatively affected by logging in the Australian tropics. By contrast, fragmentation affects a broad range of bird species—omnivores, insectivores, frugivores and nectarivores— and including virtually all species negatively affected by logging.
The effects of logging on mammals to some extent mirrors those on birds, with terrestrial and insectivorous squirrels and civets appearing most severely affected by logging. These results are based on fewer data than those for birds. No detailed studies have been conducted on the effects of fragmentation on Sundaic mammals, although Meijaard et al. (in press) used distribution data of island mammals in the Sundaic region to model the effects of fragmentation on mammal survival in small forest areas.
Overall, it appears that increased hunting pressure in logging concessions (because of high local demands for bush meat and increased road density after logging) is having a very high impact on species that are targeted by hunters (ungulates, primates, specific bird species, such as hornbills and Straw-headed Bulbul Pycnonotus zeylanicus, and turtles and crocodiles). Logging seems to primarily affect species that rely on abundant invertebrate populations in the understorey, while some non-flying arboreal species seem to be affected by the increased opening of the forest canopy. Fragmentation, finally, appears to mostly affect species that occur at low densities and have large home ranges (carnivores, and migrating species). More work will soon be conducted on the individual contribution of each of these factors to species declines following logging, but the available data already allow some tentative conclusions and recommendations for improved production forestry management.